Ship propulsion engineering
Ship Sea Trials
A good efficiency can only be achieved by proper component study.
A sea trial is the process of testing a vessel under real operating conditions to verify that its propulsion system, maneuverability, and onboard equipment perform according to design specifications. Whether carried out on a newly built ship or after a refit, these tests provide the objective data that no simulation can fully replace. We have the equipment and experience to perform trials in the following disciplines:
- Power measurements on the shaft by toque meter
- Maneuverability
- Accelerations and movements of the ship in operation
- Electrical magnitudes
- Flow rates in pipes
Power measurements on the shaft by torque meter
We have portable torque meters to measure the real torque absorbed by the propeller, determining very precisely the engine power at different operating regimes. Installed directly on the shaft without permanent modifications, our instrumentation captures delivered power (PD) across the full RPM range, from slow steaming to maximum continuous rating. This is the foundation of any rigorous procedure: accurate shaft power data allows us to build speed-power curves, compare results against design predictions, and certify propulsive efficiency. Any discrepancy between measured and predicted values is immediately flagged and investigated, providing shipyards and shipowners with a defensible, data-backed performance record.
Maneuverability
Recording the trajectories of the ship in the different types of maneuver by means of an inertial measurement unit IMU, which allows a very accurate recording of the movements of the ship in the six degrees of freedom. During this test it is usual to simultaneously record the rudder angles, validating the capacities prescribed by IMO such as tactical diameter, crash stop and Zig Zag. The IMU data is post-processed to generate clean trajectory plots and quantitative maneuverability indices, directly comparable against class society requirements and the vessel’s own design model. This procedure is applicable to all vessel types, from fishing vessels and ferries to offshore units and naval patrol boats.
Accelerations and movements of the ship in operation
- Pitch
- Roll
- Heave
- Speed loss
- Acceleration in the trawl blocks
- Slamming, etc.
For any sea trial boat operating in demanding sea states (trawlers, patrol vessels, offshore support) measuring motions in real conditions is critical for crew safety and strutural integrity.
“Seakeeping behavior can be register measuring accelerations in six degrees of freedom.”
Electrical magnitudes
Power and consumption measurements in diesel-generator sets and shaft generators. Active and reactive power recording, on a one-off or semi-permanent basis, installing a recording equipment during an entire campaign. Particularly relevant for vessels with hybrid propulsion or complex power management systems.
Our certified instruments measure voltage, current, power factor, and harmonic distortion across all generator sets simultaneously, providing a complete picture of the vessel’s electrical balance at each operating point. This data is essential for optimising fuel consumption, detecting underperforming units, and validating load management strategies during offshore trials. For vessels undergoing efficiency audits or emissions compliance reviews, the measurement campaign can be extended to cover a full operational cycle at sea.
Flow rates in pipes
Flow measurement in pipes using non-invasive ultrasonic flowmeters. This measurement allows determining the fuel consumption of diesel engines as well as other flow rates such as cooling circuits, without modifying the installation. Delivers reliable consumption data across load conditions, invaluable for performance optimization and emissions reporting. Because the sensors clamp directly onto the pipe exterior, installation requires no downtime, no hot work, and no interruption to vessel operations, making this one of the cleanest and most practical onboard measurements available. Flow data is recorded synchronously with shaft power and electrical readings, enabling a full energy balance of the propulsion plant across all tested regimes.
Frequently asked questions
What is the purpose of a propulsion trial?
This procedure verifies that a vessel’s propulsion system, maneuvering behavior, and onboard equipment perform according to design specifications and contractual guarantees. It is mandatory for new builds and recommended after major refits. Beyond compliance, a well-executed performance test generates a permanent baseline (speed-power curves, fuel consumption data, and maneuvering indices) that serves as a reference throughout the vessel’s operational life for troubleshooting, insurance, and resale purposes.
What does a standard sea trial checklist include?
A standard sea trial checklist covers shaft power measurements, speed-power curves, maneuvering tests (tactical diameter, crash stop, zig-zag), seakeeping motions, electrical measurements, and fuel flow rates. The exact scope depends on the vessel type and applicable class society rules. For fishing vessels and offshore units, acceleration and slamming measurements are typically added. For hybrid or diesel-electric vessels, the electrical measurement campaign is extended to cover load-sharing and generator sequencing across all operating modes.
Can VICUSdt perform propulsion trials outside Spain?
Yes. Our team is mobilized to shipyards and ports across Europe and internationally. We have conducted offshore propulsion trials in Atlantic, Mediterranean, and North Sea waters, working directly with shipyards, naval architects, and shipowners on-site. All instrumentation is portable and transport-ready, and our engineers are experienced in coordinating with local port authorities and classification society surveyors to ensure a smooth, compliant execution.
